/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.server.ai;

import java.util.logging.Logger;

import javax.xml.stream.XMLStreamException;

import net.sf.freecol.common.io.FreeColXMLReader;
import net.sf.freecol.common.io.FreeColXMLWriter;
import net.sf.freecol.common.model.Colony;
import net.sf.freecol.common.model.Europe;
import net.sf.freecol.common.model.FreeColGameObject;
import net.sf.freecol.common.model.Game;
import net.sf.freecol.common.model.Goods;
import net.sf.freecol.common.model.GoodsType;
import net.sf.freecol.common.model.Locatable;
import net.sf.freecol.common.model.Location;
import net.sf.freecol.common.model.Direction;
import net.sf.freecol.common.model.PathNode;
import net.sf.freecol.common.model.Settlement;
import net.sf.freecol.common.model.Unit;
import net.sf.freecol.common.util.LogBuilder;
import net.sf.freecol.server.ai.mission.Mission;

import org.w3c.dom.Element;


/**
 * Objects of this class contains AI-information for a single {@link Goods}.
 */
public class AIGoods extends TransportableAIObject
{

    private static final Logger logger = Logger.getLogger( AIGoods.class.getName( ) );

    /** The underlying goods. */
    private Goods goods;

    /** The destination location for the goods. */
    private Location destination;


    /**
     * Creates a new uninitialized <code>AIGoods</code>.
     *
     * @param aiMain The main AI-object.
     * @param id The object identifier.
     */
    public AIGoods( AIMain aiMain, String id )
    {
        super( aiMain, id );

        this.goods = null;
        this.destination = null;
    }

    /**
     * Creates a new <code>AIGoods</code>.
     *
     * @param aiMain The main AI-object.
     * @param location The location of the goods.
     * @param type The type of goods.
     * @param amount The amount of goods.
     * @param destination The destination of the goods. This is the
     *      <code>Location</code> to which the goods should be transported.
     */
    public AIGoods( AIMain aiMain, Location location, GoodsType type,
                    int amount, Location destination )
    {
        this( aiMain, getXMLElementTagName( ) + ":" + aiMain.getNextId( ) );

        this.goods = new Goods( aiMain.getGame( ), location, type, amount );
        this.destination = destination;

        uninitialized = false;
    }

    /**
     * Creates a new <code>AIGoods</code> from the given
     * XML-representation.
     *
     * @param aiMain The main AI-object.
     * @param element The root element for the XML-representation 
     *       of a <code>Wish</code>.
     */
    public AIGoods( AIMain aiMain, Element element )
    {
        super( aiMain, element );

        uninitialized = getGoods( ) == null;
    }

    /**
     * Creates a new <code>AIGoods</code> from the given
     * XML-representation.
     *
     * @param aiMain The main AI-object.
     * @param xr The input stream containing the XML.
     * @exception XMLStreamException if a problem was encountered
     *      during parsing.
     */
    public AIGoods( AIMain aiMain,
                    FreeColXMLReader xr ) throws XMLStreamException
    {
        super( aiMain, xr );

        uninitialized = getGoods( ) == null;
    }


    /**
     * Gets the goods this <code>AIGoods</code> is controlling.
     *
     * @return The <code>Goods</code>.
     */
    public final Goods getGoods( )
    {
        return goods;
    }

    /**
     * Sets the goods this <code>AIGoods</code> is controlling.
     *
     * @param goods The new <code>Goods</code>.
     */
    public final void setGoods( Goods goods )
    {
        this.goods = goods;
    }

    /**
     * Gets the type of goods this <code>AIGoods</code> is controlling.
     *
     * @return The <code>GoodsType</code>.
     */
    public final GoodsType getGoodsType( )
    {
        return goods.getType( );
    }

    /**
     * Gets the amount of goods this <code>AIGoods</code> is controlling.
     *
     * @return The amount of goods.
     */
    public final int getGoodsAmount( )
    {
        return goods.getAmount( );
    }

    /**
     * Sets the amount of goods this <code>AIGoods</code> is controlling.
     *
     * @param amount The new amount of goods.
     */
    public final void setGoodsAmount( int amount )
    {
        goods.setAmount( amount );
    }


    // Internal

    /**
     * Goods leaves a ship.
     *
     * @param amount The amount of goods to unload.
     * @return True if the unload succeeds.
     */
    private boolean leaveTransport( int amount )
    {
        if ( ! ( goods.getLocation( ) instanceof Unit ) ) return false;
        final Unit carrier = ( Unit ) goods.getLocation( );
        final GoodsType type = goods.getType( );
        if ( carrier.getGoodsCount( type ) < amount ) return false;

        final AIUnit aiCarrier = getAIMain( ).getAIUnit( carrier );
        int oldAmount = carrier.getGoodsCount( type );
        boolean result = AIMessage.askUnloadGoods( type, amount, aiCarrier );
        if ( result )
        {
            int newAmount = carrier.getGoodsCount( type );
            if ( oldAmount - newAmount != amount )
            {
                // FIXME: sort this out.
                // For now, do not tolerate partial unloads.
                logger.warning( "Partial goods unload, expected: " + amount
                                        + ", got: " + ( oldAmount - newAmount ) );
                result = false;
            }
            logger.fine( "Unloaded " + amount + " " + type
                                 + " from " + oldAmount + " leaving " + newAmount
                                 + " off of " + carrier + " at " + carrier.getLocation( ) );
        }
        return result;
    }


    // Implement TransportableAIObject

    /**
     * {@inheritDoc}
     */
    @Override
    public Locatable getTransportLocatable( )
    {
        return getGoods( );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Location getTransportSource( )
    {
        return ( goods == null ) ? null : goods.getLocation( );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public Location getTransportDestination( )
    {
        return this.destination;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setTransportDestination( Location destination )
    {
        this.destination = destination;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public PathNode getDeliveryPath( Unit carrier, Location dst )
    {
        if ( dst == null ) dst = Location.upLoc( getTransportDestination( ) );

        PathNode path = ( goods.getLocation( ) == carrier ) ? carrier.findPath( dst )
                : ( goods.getLocation( ) instanceof Unit ) ? null
                : carrier.findPath( goods.getLocation( ), dst, null, null );
        if ( path != null ) path.convertToGoodsDeliveryPath( );
        return path;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public PathNode getIntermediatePath( Unit carrier, Location dst )
    {
        return null; // NYI
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean carriableBy( Unit carrier )
    {
        return carrier.couldCarry( getGoods( ) );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean canMove( )
    {
        return false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean leaveTransport( )
    {
        return leaveTransport( null );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean leaveTransport( Direction direction )
    {
        if ( direction != null ) return false;
        return leaveTransport( goods.getAmount( ) );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public boolean joinTransport( Unit carrier, Direction direction )
    {
        if ( direction != null ) return false;
        final AIUnit aiCarrier = getAIMain( ).getAIUnit( carrier );
        if ( aiCarrier == null ) return false;

        final GoodsType type = goods.getType( );
        boolean failed = false;
        int oldAmount = carrier.getGoodsCount( type ),
                goodsAmount = goods.getAmount( ),
                amount = Math.min( goodsAmount, carrier.getLoadableAmount( type ) );
        if ( AIMessage.askLoadGoods( goods.getLocation( ), type, amount,
                                     aiCarrier ) )
        {
            setGoods( new Goods( getGame( ), carrier, type, amount ) );
            final Colony colony = carrier.getColony( );
            if ( colony != null )
            {
                getAIMain( ).getAIColony( colony ).removeExportGoods( this );
            }
        }
        logger.fine( "Loaded " + amount + " " + type.getSuffix( )
                             + " over " + oldAmount + " leaving " + ( goodsAmount - amount )
                             + " onto " + carrier + " at " + carrier.getLocation( ) );
        return ! failed;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String invalidReason( )
    {
        String reason = Mission.invalidTransportableReason( this );
        Settlement s;
        return ( reason != null )
                ? reason
                : ( goods.getLocation( ) instanceof Unit
                && destination instanceof Settlement
                && ! ( ( Unit ) goods.getLocation( ) )
                .getOwner( ).owns( s = ( Settlement ) destination ) )
                ? "transportableDestination-" + s.getName( ) + "-captured-by-"
                + s.getOwner( ).getDebugName( )
                : null;
    }


    // Override AIObject

    /**
     * Disposes this object.
     */
    @Override
    public void dispose( )
    {
        dropTransport( );
        if ( destination != null )
        {
            if ( destination instanceof Colony )
            {
                AIColony aic = getAIMain( ).getAIColony( ( Colony ) destination );
                if ( aic != null ) aic.removeExportGoods( this );
            }
            else if ( destination instanceof Europe )
            {
                // Nothing to remove.
            }
            else
            {
                logger.warning( "Unknown type of destination: " + destination );
            }
            destination = null;
        }
        goods = null;
        super.dispose( );
    }

    /**
     * Checks the integrity of a this AIGoods.
     *
     * @param fix Fix problems if possible.
     * @return Negative if there are problems remaining, zero if
     *     problems were fixed, positive if no problems found at all.
     */
    @Override
    public int checkIntegrity( boolean fix )
    {
        int result = super.checkIntegrity( fix );
        String why = ( result < 0 ) ? "super"
                : ( goods == null ) ? "null-goods"
                : ( goods.getType( ) == null ) ? "null-goods-type"
                : ( goods.getAmount( ) <= 0 ) ? "non-positive-goods-amount"
                : ( goods.getLocation( ) == null ) ? "null-location"
                : ( ( ( FreeColGameObject ) goods.getLocation( ) ).isDisposed( ) ) ? "disposed-location"
                : null;
        if ( destination != null
                && ( ( FreeColGameObject ) destination ).isDisposed( ) )
        {
            if ( fix )
            {
                logger.warning( "Fixing disposed destination for " + this );
                destination = null;
                if ( result > 0 ) result = 0;
            }
            else
            {
                why = "disposed-destination";
            }
        }
        if ( why != null )
        {
            logger.finest( "checkIntegrity(" + this + ") = " + why );
            result = - 1;
        }
        return result;
    }


    // Serialization

    private static final String DESTINATION_TAG = "destination";


    /**
     * {@inheritDoc}
     */
    @Override
    protected void writeAttributes( FreeColXMLWriter xw ) throws XMLStreamException
    {
        super.writeAttributes( xw );

        if ( destination != null )
        {
            xw.writeAttribute( DESTINATION_TAG, destination.getId( ) );
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void writeChildren( FreeColXMLWriter xw ) throws XMLStreamException
    {
        super.writeChildren( xw );

        if ( goods != null ) goods.toXML( xw );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void readAttributes( FreeColXMLReader xr ) throws XMLStreamException
    {
        super.readAttributes( xr );

        final Game game = getAIMain( ).getGame( );

        destination = xr.getLocationAttribute( game, DESTINATION_TAG, false );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void readChildren( FreeColXMLReader xr ) throws XMLStreamException
    {
        super.readChildren( xr );

        if ( getGoods( ) != null ) uninitialized = false;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected void readChild( FreeColXMLReader xr ) throws XMLStreamException
    {
        final String tag = xr.getLocalName( );

        if ( Goods.getXMLElementTagName( ).equals( tag ) )
        {
            if ( goods != null )
            {
                goods.readFromXML( xr );
            }
            else
            {
                goods = new Goods( getAIMain( ).getGame( ), xr );
            }

        }
        else
        {
            super.readChild( xr );
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString( )
    {
        LogBuilder lb = new LogBuilder( 64 );
        lb.add( "[", getId( ), " ", goods );
        if ( goods != null ) lb.add( " at ", goods.getLocation( ) );
        lb.add( " -> ", destination );
        AIUnit transport = getTransport( );
        if ( transport != null ) lb.add( " using ", transport.getUnit( ) );
        lb.add( "/", getTransportPriority( ), "]" );
        return lb.toString( );
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getXMLTagName( ) { return getXMLElementTagName( ); }

    /**
     * Gets the tag name of the root element representing this object.
     *
     * @return "aiGoods"
     */
    public static String getXMLElementTagName( )
    {
        return "aiGoods";
    }
}
